[FFmpeg-cvslog] rv10/20: Fix a buffer overread caused by losing track of the remaining buffer size.

[Alex Converse]

ffmpeg | branch: release/0.8 | Alex Converse <alex.converse at gmail.com> | Thu Mar  1 14:07:22 2012 -0800| [b56b7b9081d5b9048732c0db171c7b6af9831bad] | committer: Reinhard Tartler

rv10/20: Fix a buffer overread caused by losing track of the remaining buffer size.

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable at libav.org
(cherry picked from commit 2f6528537fdd88820f3a4683d5e595d7b3a62689)

Signed-off-by: Reinhard Tartler <siretart at tauware.de>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=b56b7b9081d5b9048732c0db171c7b6af9831bad
---

 libavcodec/rv10.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/libavcodec/rv10.c b/libavcodec/rv10.c
index 223500c..3ac0378 100644
--- a/libavcodec/rv10.c
+++ b/libavcodec/rv10.c
@@ -653,8 +653,12 @@ static int rv10_decode_frame(AVCodecContext *avctx,
 
     if(!avctx->slice_count){
         slice_count = (*buf++) + 1;
+        buf_size--;
         slices_hdr = buf + 4;
         buf += 8 * slice_count;
+        buf_size -= 8 * slice_count;
+        if (buf_size <= 0)
+            return AVERROR_INVALIDDATA;
     }else
         slice_count = avctx->slice_count;
 
@@ -693,7 +697,7 @@ static int rv10_decode_frame(AVCodecContext *avctx,
         s->current_picture_ptr= NULL; //so we can detect if frame_end wasnt called (find some nicer solution...)
     }
 
-    return buf_size;
+    return avpkt->size;
 }
 
 AVCodec ff_rv10_decoder = {